Of the 53 girls between the ages of 14 and 17 who are in state custody, 31 either have given birth or are expecting, said Child Protective Services spokesman Darrell Azar.
"It shows you a pretty distinct pattern, that it was pretty pervasive," Azar said Monday after releasing the latest figures.
Under Texas law, children under the age of 17 generally cannot consent to sex with an adult. A girl can get married with parental permission at 16, but none of these girls is believed to have a legal marriage under state law.
Church officials have denied that any children were abused at the Yearning For Zion Ranch in Eldorado and say the state's actions are a form of religious persecution.
State officials took custody of all 463 children at the ranch controlled by the Fundamentalist Church of Jesus Christ of Latter Day Saints, saying a pattern of teen girls forced into underage "spiritual" marriages and sex with much older men created an unsafe environment for the sect's children.
Of the 463 children, 250 are female, reports CBS News correspondent Hari Sreenivasan.
FLDS spokesman Rod Parker said he does not believe the CPS count is accurate. He said that from talking to ranch residents, he believes at least 17 of the girls may actually be adults but have been labeled by child welfare authorities as minors.
Agency officials have called into question claims of adulthood among the girls since the raid and have in some cases disputed documentation provided, saying the girls look younger than 18. Because many FLDS members share similar names and have complicated family relationships, identifying all of the children taken into custody has been a challenge.
"I do have serious questions about how they are determining age in there," said Parker, who is trying to get a better count from FLDS families.
He said the sect is at a disadvantage in proving names and ages because law enforcement confiscated every document that might show family relationships.
The latest information from CPS comes with "absolutely nothing to back it up other than it's coming from them, and they think we should trust them," Parker said.
CPS said they are slowly getting some cooperation from girls, who initially claimed to be older than their actual age, reports Sreenivasan.
All the children are supposed to get individual hearings before June 5 to help determine if they'll stay in state custody or if their parents may be able to take steps to regain custody.
Civil liberties groups and lawyers for the children have criticized the state for sweeping all the children, from nursing infants to teen boys, into foster care when only teen girls are alleged to have been sexually abused.
No one has been charged since the raid, which was prompted by a series of calls to a domestic abuse hot line, purportedly from a 16-year-old girl forced into a marriage recognized only by the sect with a man three times her age. That girl has not been found and authorities are investigating whether the call was a hoax.
On Monday, CPS also revised its total count of children in state custody to 463, up one from Friday. Azar said the change resulted from finally getting the children out of temporary housing in the San Angelo Coliseum and into foster facilities around the state where they could get a more accurate count.
Children 13 and younger are about evenly split - 197 girls and 196 boys - but there are only 17 boys aged 14 to 17 compared with the 53 girls in that age range.
Azar said the numbers could still change slightly because authorities have not seen documentation on all the children and have struggled to positively identify everyone.
The sect, that broke from the Church of Jesus Christ of Latter-day Saints more than a century ago, believes polygamy brings glorification in heaven. Its leader, Warren Jeffs, is revered as a prophet. Jeffs was convicted last year in Utah of forcing a 14-year-old girl into marriage with an older cousin.